1. Technical Field
The present invention relates to a classifying device, a classifying program, and a classifying method for classifying an image into regions of three or more classes using a graph-cut technique.
2. Background Art
In recent years, energy minimization using a minimum graph cut (graph cut) algorithm is being frequently applied to image processing. In particular, methods for efficiently solving a problem of image segmentation (region segmentation) as an energy minimization problem have been proposed.
Ishikawa has extended a graph-cut technique that partitions an image of interest into two classes by minimizing a second-order energy function to allow partitioning into multiple ordered classes (see H. Ishikawa, “Exact optimization for Markov random fields with convex priors”, IEEE PAMI, Vol. 25, No. 10, pp. 1333-1336, 2003, hereinafter, Non-Patent Literature 1).
Further, Kolmogorov, et. al., have proposed a method for minimizing a third-order energy when partitioning into two classes is performed. Kolmogorov, et. al., have also introduced a method using a third-order energy when partitioning into multiple classes is performed. This method allows solving a multiple-class problem by repeatedly solving two-class problems to label multiple classes, where the multiple classes may not be multiple ordered classes (see V. Kolmogorov and R. Zabih, “What Energy Functions Can Be Minimized via Graph Cuts?”, IEEE PAMI, Vol. 26, No. 2, pp. 147-159, 2004, hereinafter, Non-Patent Literature 2).